These terms describe altered states that are associated with brain injury (e.g., trauma, stroke, tumor) or with developmental deficits. Although the list deals with primarily CNS-associated disorders, in some cases the term does not distinguish between a CNS cause or a peripheral or neuromuscular cause. Terms that are primarily psychiatric diagnoses (e.g., schizophrenia) are not included.

AGNOSIA is a general term for a loss of ability to recognize objects, people, sounds, shapes, or smells; that is, the inability to attach appropriate meaning to objective sense-data. It usually is used when the primary sense organ involved is not impaired. APHASIA is a general term relating to a loss of language ability. APRAXIA is a general term for disorders of practice. These conditions are usually caused by brain injury due to trauma, stroke and/or tumor.

Many of these terms have two synonymous forms that differ in whether the word starts with a- or with dys- such as alexia and dyslexia. Here the a- form is usually defined and the other is noted as "syn:", except when the dys- form is the more common usage. (If you cannot find a term in one of these forms, look for it in the other. All other synonyms are defined in both forms.)

Sources: These definitions are paraphrased from definitions in a large number or print and online dictionaries. Thus this list is not meant to be considered my own, but rather is a compilation.

Note: When a word appears in italics, that indicates it is defined elsewhere in this list.

abulia - Loss of will power or ability to make decisions.

acataphasia - Inability to formulate a statement or expression in an organized manner.

acoria (syn: akoria) - Inability to feel satiated, regardless of how much is eaten.

adiadochokinesia (syn: dysdiadocchokinesia) - Inability to perform rapidly alternating movements, that is to stop a movement and follow it with another in an opposite direction.

ageusia - Impaired sense of taste.

agnosia -A general term for a loss of ability to recognize objects, people, sounds, shapes, or smells; that is, the inability to attach appropriate meaning to objective sense-data. It usually is used when the primary sense organ involved is not impaired.

agraphia - Inability to express thought in written language (usually not due to mechanical disfunction), (synonym dysgraphia).

agraphesthesia - Inability to identify a letter or number being written on some part of the body.

akathisia - Motor restlessness; an inability to sit still. Often caused by defects in the extrapyramidal system.

anomia (syn: dysnomia) - General term for the inability to name objects. This can be limited to inability to name objects in semantic categories such as living things, inanimate things, fruits and vegetables, colors, animals, body parts, furniture, etc. Many of these limited conditions are given special names. (A related condition is a failure to comprehend syntactical structures, but this has no specific name.)

anopsia - Blindness.

anorexia - Loss or appetite. A pathological fear of eating, in order to avoid weight gain.

anosmia (syn: anosphrasia) - Loss of the sense of smell.

anosognosia - Unawareness of, denial of, or failure to recognize one's own neurological deficit. For example someone paralyzed on their left side may claim they can move their left arm normally.

anosphrasia (syn: anosmia) - Loss of the sense of smell.

apastia - Refusal to eat.

apathy - Lack of interest or concern.

aphasia (syn: dysphasis) - This is the general term that literally means "no speech." It refers to any impairment of the ability to use and/or understand words and can be used to describe loss of one or more of the following abilities: ability to speak; ability to write; understand speech; understand written words. Major subcategories include: Broca's aphasia, in which one can comprehend speech, but not produce it; and, Wernicke's aphasia in which one can produce speech but not comprehend speech.

aphemia - Inability to speak words, but able to make other sounds.

aphonia (dysphonia) - Loss of ability to speak; inability to produce speech sounds. Distinguished from the motor defect called dysarthria, which is imperfect articulation of speech due to disturbances of muscular control.

apraxia (syn: dyspraxia)- Difficulty in performing a learned movement or coordinated motor activity even though understanding, motor function coordination, and sensation are intact. Specific apraxias may be limited to a certain group of functions, such as inability to construct a simple structure from blocks, or inability to dress oneself. Related to akinesia.

dyschiria - Inability to tell which side of the body has been touched. Related to allesthesia.

dyschronation - Lack of a sense of relativity in the consciousness of time.

dysergia - Motor impairment due to axonal transmission failure.

dyslexia - A condition in which an individual with normal vision is unable to properly interpret or produce written language. Individuals can see and recognize letters but have difficulty spelling and writing words. They have no impairment of object or picture identification. Dyslexia may have distinguishable subforms (such as alexia), and is not related to intelligence. Dyslexia is more common in males and is often first recognized as a reading difficulty in the early school grade.

dysesthesia (syn:dysaesthesia) - Abnormal sensations of the skin. Somtimes used more generally for the impairment of any of the senses. Related to dysaphia.